Abstract: Process for selectively separating precious metal such as silver and gold from a chloride solution of the precious metals and other heavy metals which involves:(a) adding finely divided activated carbon to the solution for reduction of gold to gold metal and absorption of the gold metal by the carbon,(b) adding an aqueous solution of an iodine compound for selective precipitation of further precious metal including the silver, if present.During steps (a) and (b) the pH is below 3 so that hydrolysis with the metal ions does not occur, and the potential of the solution during step (b) is such that no substantial decomposition of the iodine compound occurs. The precipitated precious metal and active carbon are separated, dried, and admixed with an iodine binder, and the resulting admixture is subjected to reduction for formation of a regulus containing the precious metal.

Abstract: Aqueous lead solutions obtained by hot chloride leaching of residues containing lead and silver ore are subjected to selective precipitation of the silver as silver sulphide, with e.g. hydrogen sulphide. The silver can then be recovered in a known manner. Lead can be precipitated from the remaining solution as a basic salt also in a known manner. If the initial residue contains copper, it is also precipitated as sulphide. The copper sulphide can be separated from the precipitate by selectively dissolving the copper with sulphuric acid under an elevated oxygen pressure. Elemental sulphur is formed and the silver sulphide can be separated from the elemental sulphur in a known manner.

Abstract: A process for recovering metallic values from arsenic-containing copper cementate sludges. The cementate is admixed with lime in an amount sufficient to form calcium sulfate by reaction with any water-soluble sulfate present in the cementate, and calcium arsenate from the arsenic present in the cementate. The admixture is roasted in an oxygen-containing atmosphere at a temperature above about 300.degree. C, to oxidize the metallic values to a state in which said values are soluble in aqueous acid. The roasted material is leached with aqueous acid to dissolve said values. The values can be recovered from the solution produced in the leaching step by known procedures. By the process of the invention, polluting by arsenic is prevented.

Abstract: Copper sulfate solution obtained by the sulfuric acid leaching of cupriferous material and containing impurities such as Fe, As, Sb, Bi, Se, Te, Sn, Pb, Cl, Ag, Hg, and PO.sub.4, are subjected to a two step purification process. In the first step, the pH is adjusted to 2.7-3.3 with, e.g. Ca(OH).sub.2, and the potential in relation to the standard hydrogen electrode is adjusted to at least 575 mv with an oxidizing agent, e.g. air. The temperature is 50.degree.-90.degree. C. Impurities precipitate and are separated. Se, Cl, and possibly Ag and Hg remain in solution and are removed in the second step, wherein the potential is reduced to below 350 mv by addition of a cupriferous reducing agent, e.g. Cu or Cu.sub.2 O. The pH is below 3 and the temperature is below 50.degree. C. Impurities precipitate as copper (I) compounds, and are separated to provide the solution in condition for the electrolysis. The copper produced is of high purity, having a conductivity of at least 58.8 mho .times. m/mm.sup.

Abstract: A method is provided for processing raw manganese nodules for the selective recovery of metal values of nickel, copper, cobalt and zinc contained therein by hydrometallurgical means. The raw nodules are suspended in water or dilute wash solution to form a suspension. The suspension and sulfuric acid are charged to a pressure vessel to provide a solid-liquid suspension of nodules and leach solution. The solid-liquid suspension of nodules and leach solution is heated in the pressure vessel to a temperature between about 150.degree. C and about 300.degree. C to cause the nickel, copper, cobalt and zinc to be selectively leached from the nodules into the leach solution to form a metal rich leach solution containing these metals and a residue, with the solid-liquid suspension having a sulfuric acid content of less than 35 g/l upon completion of the leaching. The metal rich leach solution containing nickel, copper, cobalt and zinc is separated from the residue.

Abstract: A process for working up of a concentrate containing Cu, Zn, and precious metal including at least one of Ag or Au. In a first stage, the concentrate or the concentrate in modified form is leached for hydrometallurgically dissolving out the copper and zinc and leaving a residue containing the precious metal, and the leach liquor is separated from the residue. In a second stage, residue is subjected to a chlorinating sulfatizing roasting, and the roasted residue is leached with a selective solvent for the precious metal, e.g. aqueous NaCl, for dissolving the precious metal out of the residue.